In recent years, an imaging apparatus (hereinafter also referred to as OCT apparatus) for imaging an object by the use of an optical coherence tomography (OCT) using interference by a low coherence light has been used in a medical field, especially in an ophthalmologic field. Because the OCT apparatus uses a characteristic of light, the OCT apparatus can acquire a tomographic image at the high resolution of about a micrometer, which is the order of a wavelength of light. When an eye to be inspected, such as a fundus, is measured here, the examinee sometimes moves, blinks, or randomly joggles (flicks) during measurement. There is a problem, consequently, that a tomographic image of an eye to be inspected, which has been acquired with an OCT apparatus, is distorted.
In order to solve the problem, Thomas M. Jorgensen et al., “Enhancing the signal-to-noise ratio in ophthalmic optical coherence tomography by image registration-method and clinical examples,” Journal of Biomedical Optics, 12(4), 041208, July/August, 2007 discloses acquiring tomographic images at the same position of an object a plurality of times, aligning those tomographic images to one another, and then averaging the tomographic images to acquire one tomographic image. The method, thereby, enables the acquisition of a tomographic image having a high S/N ratio and a high image quality. At this time, there is the possibility that displacement between the position of the tomographic image acquired first and that of the tomographic image acquired last becomes large during acquiring the tomographic images a plurality of times. It will be appreciated that this makes it difficult to align the tomographic images and that the displacement makes it impossible to improve the image quality of the tomographic images as a result, even if the averaging is performed. For this reason, it can be said that it is preferable to perform imaging speedily from the point of view of making a tomographic image have high image quality at the time of imaging an eye to be inspected.
Furthermore, Published Japanese Translation of a PCT Application No. 2008-508068 discloses the OCT radiating a plurality of points of lights to a pupil in order to acquire the three-dimensional structure of the pupil.